How is sensitivity defined in the context of a medical test?

Sensitivity in the context of a medical test refers to the ability of the test to correctly identify individuals who have the disease. Specifically, it is defined as the proportion of true positive results among all individuals who actually have the disease. This measure is crucial because it highlights how effective a test is at detecting a condition, ensuring that patients who are truly affected are not missed.

A high sensitivity indicates that the test is good at ruling out the disease when the result is negative, which is particularly important for conditions where early detection is vital for effective treatment. Consequently, understanding sensitivity helps healthcare providers decide on the most appropriate diagnostic tools and interpret test results accurately.

The other choices represent different concepts related to diagnostic testing. For instance, the proportion of positive test results among healthy individuals pertains to specificity, while the true negatives among those without the disease would also relate to specificity rather than sensitivity. The likelihood that a negative test indicates the absence of disease captures aspects related to the predictive value of a test, which is a separate consideration from sensitivity itself.